1. Field of the Invention
The invention disclosed herein relates to computer network communications and, in particular, network management protocols.
2. Description of the Related Art
In the well-known Wide Area Network (WAN) architecture, all communications paths (or links) are point to point. In such networks, the nodes (or host computers) communicate with each other directly. Reliable WAN link up/link down status mechanisms are well known at both the physical layer and the data link layer (layers 1 and 2 of the well-known open systems Interconnect [OSI] Reference Model). These status mechanisms allow link faults to be determined in tens of milliseconds to one or two seconds.
However, in Local Area Network (LAN) architectures status determination is not as readily available. In part because LAN network protocols, such as Ethernet, are connectionless and support multiple accesses, several problems arise.
Firstly, an Ethernet LAN (by far the most common) can be partitioned into multiple subnetworks or segments. A given node (such as, but no limited to, a host computer, load balancing device, or router) on such a LAN is not aware of any segmentation. If a node faults, there is not necessarily any notification (e.g. a “loss of carrier” signal) to other nodes on its segment or to other segments. Secondly, there is generally no “keep alive” or “link up” check mechanism to determine whether the link or links to a particular node are working or if the node is still “listening” or has left the segment.
What is needed is a fast, reliable link up/link down statusing protocol operating on top of the existing Ethernet protocol in layer 2. Such a protocol would provide a ready means of determining network integrity and readiness. Furthermore, such a protocol must have multiple access capabilities (a “multi-access” protocol) and be compatible with the Ethernet protocol generally.